Am J C/in Nutr 1995;61:1277-83. Printed in USA. © 1995 American Society for Clinical Nutrition 1277 A placebocontrolled parallel study of the effect of two types of coffee oil on serum lipids and transaminases: identification of chemical -substances involved in the cholesterol- raisi ng effect of coffee’ Jeroen van Rooij, Gerrit HD van der Stegen, Rik C Schoemaker, Cees Kroon, Jacobus Burggraaf Leny Hollaar, Ton FFP Vroon, Augustinus HM Smelt, and Adam F Cohen ABSTRACT In a randomized double-blind parallel study in 36 subjects the effect on serum cholesterol of a daily dose of 2 g lipid extracted from green Arabica and Robusta coffee beans was studied. Arabica oil elevated serum total cholesterol by 1.1 mmol/L (95% Cl for the difference from placebo: 0.41, 1.73 mmol/L); the effect of robusta oil (+0.5 mmolfL) was not statis- tically significant (95% CI: -0.01, 0.92 mmol/L). Arabica oil also raised plasma triglycerides by 0.8 mmol/L (95% CI: 0.26, 1.25 mmol/L). The effect of robusta oil on triglycerides was +0.14 mmol/L and not significant (95% CI: -0.26, 0.42 mmol/L). In the 12 subjects taking arabica oil an average serum alanine amino- transferase elevation of 18 U/L (95% CI: 9.4, 28.4 U/L) was observed. Because only arabica oil contains kahweol and arabica coffee contains more cafestol than does robusta oil, this is further evidence for the role of diterpenes in the rise of serum cholesterol and alanine aminotransferase after consumption of boiled coffee. Am J C/in Nutr1995;61:1277-83. KEY WORDS Coffee, cholesterol, serum lipids, triglycer- ides, transaminases, liver biochemistry, kahweol, cafestol, diterpenes INTRODUCTION The association between coffee drinking and coronary heart disease is inconclusive. Several population studies revealed an increased risk for coronary heart disease in heavy coffee drink- ers (1), but other studies could not corroborate this association (2, 3). In a recent meta-analysis no clear association between coffee drinking and coronary heart disease was found (4). However, in Scandinavia, where large quantities of boiled unfiltered coffee are consumed (5), a clear relation between coffee consumption and coronary heart disease was demon- strated (6). Population studies concerning the influence of coffee con- sumption on serum cholesterol also reveal conflicting data. In a review article (7), it was concluded that a positive correlation between coffee intake and serum cholesterol concentration was present in approximately two-thirds of the studies on this subject with an indication of a dose-response relation in some of the studies (8-10). Differences in the method of preparation of coffee may explain the difference in outcomes in the different populations that were examined (5, 9-14). Intervention studies revealed a significant rise of serum total cholesterol and low-density-lipoprotein-(LDL) cholesterol con- centrations after consumption of boiled coffee for 6 wk (8, 15-17). Because filtered coffee and tea do not affect serum cholesterol concentrations (8, 9, 13, 15, 17), caffeine is not likely to be responsible for the cholesterol-elevating effect of coffee. In one intervention study a rise in the serum concen- trations of LDL cholesterol and apolipoprotein B was found if subjects changed from caffeinated coffee to decaffeinated coffee (18). Boiled coffee contains a lipid fraction that does not pass through a paper filter, and after consumption of boiled coffee that is subsequently filtered, no rise in serum cholesterol was detected (16, 19). Administration of a lipid-enriched fraction from boiled coffee to 10 healthy volunteers led to a rise in serum cholesterol (23%), LDL cholesterol (29%), and triglyc- erides (55%) after 6 wk of administration (20). After supple- mentation had ended, these concentrations returned to baseline. Coffee oil consists of triglycerides, fatty acid esters of diter- penes and sterols, free sterols, free diterpenes, phospholipids, and other unsaponifiables (20, 21). The main fatty acids in coffee oil in descending order of quantity are linoleic, palmitic, oleic, stearic, and arachidic acids. Typical for coffee oil are the diterpenes (kahweol, cafestol, and 16-o-methylcafestol), which are present mainly as fatty acid esters. In the oil of roasted coffee small amounts of monodehydrated pyrolysis products of the kahweol and cafestol esters occur as well (22). Oil from arabica coffee contains fatty acid esters of kahweol and cafestol, whereas oil from robusta coffee contains lower I From the Center for Human Drug Research, the Department of Car- diology, and the Department of Internal Medicine, University Hospital Leiden, Leiden, Netherlands, and SARA LEEfDouwe Egberts, Department of Research and Quality, Utrecht, Netherlands. 2 Supported by SARA LEE/Douwe Egberts, Utrecht, Netherlands. 3 Address reprint requests to AF Cohen, Center for Human Drug Re- search, University Hospital Leiden, P0 Box 960(), 2300 RC Leiden, Netherlands. Received May 23, 1994. Accepted for publication February 9, 1995. by guest on December 4, 2015 ajcn.nutrition.org Downloaded from